Break-away cradle or sub-frame mount and retainer washer assembly

ABSTRACT

An isolator assembly ( 20 ) such as a cradle mount or a body mount assembly incorporates break-away features. An insert ( 70,70 ′) includes a thinned cross-sectional region ( 100 ) or a gap/interface ( 90 ) between insert portions ( 70   a,    70   b ) that allow a bolt ( 24 ) to break-away under a predetermined load in a fore direction ( 80 ) and an aft direction ( 90 ). In addition, a retainer washer ( 50 ) may have an irregular configuration such as a tear-drop or clover-leaf configuration that cooperates with the insert ( 70, 70 ′) to allow the isolator assembly ( 20 ) to pull away in the negative z-direction under a predetermined load.

BACKGROUND OF THE INVENTION

The present invention relates to an improved isolator assembly thatsecures a body, such as a vehicle body, to an associated support, suchas a vehicle frame or cradle, and absorbs vibrations or shockstherebetween. More particularly, the invention relates to a body orcradle mount assembly, here more generally referred to as an isolatorassembly, as particularly used in the automotive industry. It will beappreciated, however, that the invention may find application in relatedfields.

Present industry standards form a “hard” joint between a vehicle bodyand a frame. Thus, during an event such as a front impact incident orside impact event, a frame or cradle of the vehicle can remain securedto the body or passenger compartment. For example, where a cradle mountassembly interconnects the body to a cradle, its function is two-fold.The cradle mount or isolator assembly isolates vibrations between thecradle and the body. Secondly, the assembly acts as an attachment pointof the cradle to the body.

In its most basic form, an isolator assembly such as a body mountassembly or cradle mount assembly includes an elastomeric member such asa block of rubber. The elastomeric/rubber member is positioned betweenthe first structure or frame of the vehicle and a second structure orvehicle body to absorb vibrations and isolate transmission of vibrationenergy and impact energy between the vehicle body and frame. A fastenerassembly extends longitudinally through the elastomeric member andincludes a retainer such as a nut on an opposite side of the frame orbody from a head end of the bolt. Thus, the frame and body are securedtogether via the isolator assembly and vibration energy is effectivelyabsorbed between these components by the elastomeric member. Of course,those skilled in the art appreciate that more complex isolatorassemblies include additional structural components and features thandescribed above.

It has been deemed desirable, however, to allow selective separationbetween the two structures, i.e., the frame and body, during a barrierevent. Heretofore, no effective design to meet this criteria has beenproposed. In addition, such a design must be easily manufactured andcost effective, while still providing acceptable vibration absorbingcharacteristics as achieved with commercially available isolatorassemblies.

SUMMARY OF INVENTION

An improved isolator assembly includes an insert configured to breakaway in a desired direction in response to a predetermined load andthereby allow the cradle or frame to separate from the vehicle body.

The isolator assembly includes an elastomeric member that couples theassociated frame to the associated body. An elongated fastener assemblysecures the elastomeric member to the associated frame and body. Aninsert is received in the elastomeric member and configured to break inat least one of fore and aft directions extending along andsubstantially perpendicular to the length of the fastener assembly.

The insert in one embodiment is generally a hollow sleeve having avariable cross-section.

In another embodiment, the insert is a split member defined by first andsecond portions.

A retainer preferably includes a break away configuration allowingseparation of the frame and body generally along an axis parallel to orcoincident with the longitudinal axis of the fastening assembly.

The retainer preferably includes small and large diameter portionsspaced around an irregular opening formed therethrough.

A primary advantage of the invention is the ability of the isolatorassembly to break away at a predetermined load.

Another advantage of the invention is the ability to control thedirection and predetermined load at which the isolator assembly breaksaway.

Still another advantage of the invention is the simple design that iseasy to manufacture and alter for various vehicle platforms or styles.

A still further advantage of the invention resides in a simplifieddesign for ease of assembly.

Still other features and benefits of the invention will become apparentto those skilled in the art upon reading and understanding the followingdetailed description.

BRIEF DESCRIPTION OF DRAWINGS

The drawings are intended to illustrate one or more preferredembodiments of the invention. The drawings, however, should not beconstrued to limit the invention to the illustrated embodiments.

FIG. 1 is an exploded perspective view of one embodiment of the isolatorassembly of the present invention.

FIG. 2 is a longitudinal cross-sectional view of the assembled isolatorassembly.

FIG. 3 is a top plan view of the isolator assembly.

FIG. 4 is an enlarged view of a portion of FIG. 3.

FIG. 5 is a cross-sectional view taken generally along the lines 5-5 ofFIG. 3.

FIG. 6 is a top plan view of a first preferred insert.

FIG. 7 is a cross-sectional view taken generally along the lines 7-7 ofFIG. 6.

FIG. 8 is a top plan view of a second preferred insert.

FIG. 9 is a cross-sectional view taken generally along the lines 9-9 ofFIG. 8.

FIG. 10 is a top plan view of a preferred retainer.

FIG. 11 is an elevational view of the retainer of FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

Turning first to FIG. 1, an isolator assembly 20, which in thisparticular illustrated embodiment is a cradle mount assembly,interconnects a body B of a vehicle to a frame F such as the illustratedcradle sleeve. More particularly, the isolator assembly includes anelastomeric or rubber member which in this embodiment comprises a firstor upper insulator 22 a and a second or lower insulator 22 b. Eachinsulator has a generally annular shape with a through-opening adaptedto receive a portion of the fastener assembly such as elongated bolt 24therethrough. Of course, it will be appreciated that the insulators mayadopt a wide array of configurations as may be required for variousneeds such as different vibration absorbing or damping rates indifferent directions, or may or may not include washers, inserts,stiffeners, etc, such as washer 25 that is associated with the upperinsulator. The washer provides a durable wear surface that interfaceswith the body B and other components of the assembly as will bedescribed in greater detail below.

The bolt includes a first end or large head 28 and is preferablythreaded at a second end 30 for threaded cooperation with a retentionclip 40. The retention clip includes nut 42. As is generally known inthe art, the elastomeric members 22, 24 absorb vibration energy thatwould otherwise be transferred between the frame and body. Thus, theupper insulator 22 abuttingly engages a first or lower surface 44 of thebody sheet metal B and abuttingly engages a first end 46 of the cradlesleeve F. The cradle sleeve F is a generally hollow, cylindrical memberthat encompasses or encloses a substantial portion of the lowerinsulator 24. Typically, the lower insulator is mold bonded to thesleeve, although this should not be deemed a limiting feature of thepresent invention. The cradle sleeve and lower insulator engage along astepped region 48 so that vibration energy is effectively transferredtherebetween.

A second or lower retainer 50 is engaged on a first or upper surface 52by the bolt head 28. A second or opposite surface 54 of the lowerretainer faces inwardly toward the lower insulator 24.

Extending axially around a shank 56 of the bolt and received radiallybetween the shank and inner diameter portions 58, 60 of the upper andlower insulators, respectively, is an insert 70. In one embodiment, theinsert 70 is formed of first and second portions 70 a, 70 b split alonga longitudinal axis that is substantially parallel to longitudinal axisLA of the fastener. The insert 70 has a central opening 72 that receivesthe shank 56 of the bolt therethrough. The insert is configured to breakaway in at least one of the fore and aft directions, i.e., substantiallyperpendicular to the longitudinal axis or length of the fastener bolt inthe area of a reduced cross-section when the fastener is a single memberor along the gap or mating edges when the insert is defined by first andsecond portions 70 a, 70 b. The fore and aft directions are generallyrepresented by reference numerals 80, 82, respectively in FIG. 3. As isparticular evident in FIGS. 3 and 4, this is the region of the thinnestcross-section of a unitary insert, or defines the gap or mating surfacebetween the first and second portions 70 a, 70 b. This is to becontrasted with the substantially larger cross-section of the insert ina direction perpendicular to the fore and aft directions. In thismanner, if sufficient load is applied to the isolator assembly, such asduring a barrier event, the frame F and body B will separate as a resultof the bolt shearing through the gap or thinned cross-section of theinsert.

It will be appreciated that the insert may adopt a wide variety ofconfigurations. For example, the split assembly illustrated in FIG. 1 isone arrangement. The split assembly is shown in greater detail in FIGS.6 and 7. The split members that comprise the insert are configured orcontoured to promote separation of the assembly in the fore and aftdirections. That is, as seen in FIG. 6, the insert portions have agenerally C-shape in the top plan view and define a generally diamondshaped opening 84 that extends the length of the split portions andsurrounds and accommodates the elongated shank of the fastener. Terminaledges 86, 88 are disposed in facing relation and define small gaps 90 oneither side that also extends along the full length or height of theinsert. These gaps allow the fastener to pass therethrough in avehicular event and provide the desired separation of the frame from thebody.

FIGS. 8 and 9 illustrate another configuration that still achieves thefore and aft break away movement or separation in the directionsrepresented by reference arrows 80, 82 in response to a barrier event.For purposes of brevity and understanding, like reference numerals witha primed suffix (e.g., 70′) refer to like elements, and new referencenumerals identify new elements. Here, the insert 70′ is a singlecomponent, i.e., not split along its length. To provide the desiredresponse to a barrier event, the insert 70′ includes thinnedcross-sections 100 in the desired fore and aft directions. For example,the convex outer surfaces 102, 104 provide a thicker cross-section indirections perpendicular to the fore and aft regions, while the thinnedcross-sections include concave perimeters regions 106, 108 that inconjunction with the generally diamond-shaped opening 84′ allow theisolator assembly to break away or separate in response to apredetermined load. In all other instances, the isolator assemblycontinues to provide effective vibration isolation between the frame andbody and an effective attachment point between these structures.

Separation in the negative z direction, along the longitudinal axis LAand the downward direction shown in FIG. 2, is also provided forbreak-away movement. Specifically, the insert 70 operatively engages orabuttingly engages the central portion of the upper surface 54 of thelower retainer. As best illustrated in FIGS. 6, 10 and 11, opening 120through the retainer has an irregular or scalloped configuration 122.Lands 124 define or separate radial recesses 126 (four in number,although it will be appreciated that a greater or lesser number of landsand recesses can be used without departing from the scope and intent ofthe invention). The bolt head engages the lands and thus is notsupported in a complete circumferential manner along the underside ofthe bolt head. Under a predetermined load imposed in the z-direction,the bolt head 28 separates from the retainer and thus allows the cradleto separate from the frame in the negative z-direction. Although atear-dropped or scalloped configuration is shown as the preferred formof opening through the lower retainer, still other configurations (e.g.,thinned regions) can be used to achieve the same result withoutdeparting from the scope and intent of the present invention.

It is also contemplated that one of the break-away features describedabove can be used independently or in combination. It is also preferablethat the configuration of the insert be easily manufactured. Forexample, an extrudable material such as aluminum is desired because ofthe ease of manufacture, whether one or two-piece. It is alsocontemplated that the insert can be formed of different materials or indifferent manners such as castings, sintered or powdered metals, steel,plastics such as thermosets, thermoplastics or composites, or othercombination of materials without departing from the scope and intent ofthe present invention. If two insert portions are used, they may bemirror images of one another, i.e., substantially identical, and tominimize manufacturing costs. On the other hand, if a unitary insert isprovided, it preferably has a cross-section that is consistentthroughout its length to thereby allow it to be easily manufactured.

It will also be appreciated that the design allows easy incorporation ofalternative features used in other isolator assemblies. For example,fore and aft bumpers 130, 132 (FIG. 5) may be provided around the insertto provide selective isolation in those directions. Water drainagefeatures may also be incorporated into the design without impacting onthe break-away features. Still further, selected components may bemanufactured to provide interlock features to facilitate ease ofassembly. For example, a groove is formed in the elastomer that isbonded to the outer surface of the insert. The groove forms one portionof an interlock that cooperates with an edge formed on the upperretainer. This allows a snap-fit interlock to facilitate assembly of theupper insulator.

The invention has been described with reference to the preferredembodiments. Obviously, modifications and alterations will occur toothers upon reading and understanding the preceding detaileddescription. It is intended that the invention be construed as includingall such modifications and alterations.

1. An isolator assembly comprising: an elastomeric member that couplesan associated frame to an associated body of an associated vehicle; afastener assembly securing the elastomeric member to one of theassociated vehicle frame and body; and means for allowing the fastenerassembly to break away in at least one of fore and aft directionsextending along and substantially perpendicular to a length of thefastener assembly.
 2. The isolator assembly of claim 1 wherein the meansfor allowing the fastener assembly to break away in the fore and aftdirections includes an insert received in the elastomeric member.
 3. Theisolator assembly of claim 2 wherein the insert is a generally hollowsleeve that has a variable cross-section.
 4. The isolator assembly ofclaim 2 wherein the insert includes first and second portions that areseparated along at least one of the fore and aft directions of thefastener assembly.
 5. The isolator assembly of claim 4 wherein theinsert first and second portions are substantially identical.
 6. Theisolator assembly of claim 2 wherein the insert has a cross-section thatvaries about its perimeter and is substantially constant along itslength.
 7. The isolator assembly of claim 1 further comprising aretainer that operatively engages one end of the insert, the retainerincluding an irregular opening therethrough that allows the isolatorassembly to separate generally along a longitudinal axis of the fastenerassembly.
 8. The isolator assembly of claim 1 further comprising aretainer member disposed on one side of the associated body oppositefrom the elastomeric member for securing the fastener assembly to theassociated body.
 9. The isolator assembly of claim 8 wherein theretainer opening includes small and large diameter portions spaced alongthe irregular opening.
 10. The isolator assembly of claim 1 furthercomprising a second elastomeric member interposed between the associatedbody and the associated frame.
 11. A cradle mount assemblyinterconnecting an associated frame and an associated body of a vehicle,the cradle mount assembly comprising: a vibration absorbing member thatcouples an associated frame to an associated body of an associatedvehicle; an elongated fastener assembly securing the vibration absorbingmember to one of the associated vehicle frame and body; an insertreceived in the vibration absorbing member and configured to break awayin at least one of fore and aft directions extending along andsubstantially perpendicular to the length of the fastener assembly; anda retainer that operatively engages one end of the insert, the retainerincluding an irregular opening therethrough that allows the isolatorassembly to separate generally along a longitudinal axis of the fastenerassembly.
 12. The isolator assembly of claim 11 wherein the insert is agenerally hollow sleeve that has a variable cross-section.
 13. Theisolator assembly of claim 11 wherein the insert includes first andsecond portions that are separated along at least one of the fore andaft directions of the fastener assembly.
 14. The isolator assembly ofclaim 13 wherein the insert first and second portions are substantiallyidentical.
 15. The isolator assembly of claim 11 wherein the insert hasa cross-section that varies about its perimeter and is substantiallyconstant along its length.
 16. An isolator assembly comprising: anelastomeric member that couples an associated frame to an associatedbody of an associated vehicle; a fastener assembly securing theelastomeric member to one of the associated vehicle frame and body; andan insert received in the elastomeric member allowing the fastenerassembly to break away in at least one of fore and aft directionsextending along and substantially perpendicular to a length of thefastener assembly.
 17. The isolator assembly of claim 16 wherein theinsert is a generally hollow sleeve that has a variable cross-section.18. The isolator assembly of claim 16 wherein the insert includes firstand second portions that are separated along at least one of the foreand aft directions of the fastener assembly.